Japanese Kokai Tokkyo Koho 3-35796 and 5-170749 disclose depsipeptide derivatives prepared by culturing microorganisms.
As depsipeptide substances having parasiticidal activity, substance PF1022 (Japanese Kokai Tokkyo Koho 3-35,796) and substance PF1022B, substance PF1022C, substance PF1022D (Japanese Kokai Tokkyo Koho 5-170,749) are known, and among these compounds the effectiveness of substance PF1022 on gastrointestinal parasites (whipworms, haemonchus, hairworms and roundworms living in the stomach and intestine) has been confirmed. This time, the object was to find a drug having a stronger effect on gastrointestinal parasites and also effective on tissue parasites (for example filariid worms living in blood vessels, lungworms living in the lungs, liver flukes living in the liver).